The present invention relates to an air-intake device for drawing air into a liquid dispenser.
A liquid dispenser is generally equipped with a rigid reservoir and with an atmospheric pump provided, in particular, with a cylindrical and conical body and with a support flange co-operating, as applicable, with an assembly ring or with an assembly cap crimped to the neck of the reservoir, while bearing against a sealing gasket surrounding the pump body.
A metered quantity or xe2x80x9cdosexe2x80x9d of liquid being dispensed generates suction in the fixed-capacity reservoir, and it is necessary to compensate for said suction by drawing in a corresponding volume of air. To this end, the pump body is provided with vent orifices suitable for putting the internal volume of the reservoir into communication with the outside during the final stage of dispensing.
Another technique for re-establishing the pressure balance necessary for the dispenser to operate properly consists in providing clearance between the fixing flange and/or the pump body and the neck of the reservoir and/or the assembly cap so as to enable air to be sucked in.
However, in all known techniques, the vent-forming means also enable liquid to leak out, especially when the level of liquid is above the vent, either by construction or by the dispenser being used specifically in the upside down position.
An object of the present invention is to solve those technical problems satisfactorily without modifying the conventional structure of dispensers.
The invention achieves this object by means of an air-intake device characterized in that it comprises a flat annular gasket-forming washer whose free edge is in leaktight abutment towards the outside under a frustoconical shoulder carried by a collar engaged over said pump body, and is capable of being deformed elastically under the effect of internal suction to enable air to be drawn in.
In a specific embodiment, said frustoconical shoulder is formed directly on the outside side wall of the body of the pump.
In another embodiment, said frustoconical shoulder is carried by a collar engaged over said pump body.
According to an advantageous characteristic, said washer is provided with at least one radial slot extending from the free edge to facilitate deforming said free edge.
According to another characteristic, when the pump is in the closed position, the inside edge of said washer is deflected inwards under stress while having a portion of its outside face in contact with said shoulder.
In a variant, the inside face of said washer is provided with a peripheral keying groove serving to receive a rib provided on the top periphery of the reservoir.
The device of the invention makes it possible for sufficient air to be drawn in, while also guaranteeing that the dispenser is airtight.
The flexibility and elasticity of the annular gasket may be adjusted as a function of the level of suction generated in the reservoir due to liquid being dispensed.
The device of the invention is applicable to precompression pumps with or without vent orifices, without it being necessary to modify their structure.